1. Technical Field
This invention relates to a film transporting system adapted to selectively advance or rewind a film roll loaded in the camera in automatic mode utilizing drive power provided by an electric motor, or the like.
2. Prior Art
Photographic cameras of various types requiring neither skill nor experience of users have become popular. With these handy cameras, upon closure of the rear cover after a film cartridge has been loaded into the camera, the built-in electric motor is actuated to transport the film roll by a sufficient amount to bring the camera in a state ready for photographing. Immediately after the first release, the motor is actuated again to advance the film roll by one frame and thereby to align the next frame with the aperture. Use of the final frame causes the motor to rewind the film roll into the cartridge.
Such cameras having automatic film advance and film rewinding typically utilize an electric motor for film transport and have a source battery loaded therein to energize the film transporter, comprising the electric motor. The source battery has a limited life and must be replaced by a fresh one if it is detected to have been consumed beyond its usable voltage level.
Sometimes the source battery is detected to have been consumed beyond its usable level with the film roll loaded in the camera and having several frames still remaining unused. With the conventional camera provided with such automatic film transporting system, either no film transport occurs or the entire film roll is forcibly rewound upon replacment of the source battery. Prior art film transporting systems have thus been accompanied with inconvenience as described hereinbelow.
With some prior art cameras, the film transporting system is not responsive to replacement of the source battery to perform any operation of film transport, such that a frame will be double exposed. The frame will be exposed once before the battery is replaced and once after the source battery is replaced, if the battery drops below the camera's operating threshold just before, or halfway through, a single frame advance. This occurs because the first photograph must be taken after replacement of the source battery and before film advance occurs.
Other prior art cameras are provided with a film transporting system responsive to replacement of the source battery to forcibly rewind the film roll. Double exposure is avoided by this method. However, the film roll is wastefully consumed, particularly when it contains many frames still remaining unused.